1. Field of the Invention
The present invention relates to an optical module and a method for manufacturing the same and more particularly to the optical module capable of optically coupling optical waveguides, each other, to be connected to optical components and to the method for manufacturing the optical module.
The present application claims priority of Japanese Patent Application No.2000-403445 filed on Dec. 28, 2000, which is hereby incorporated by reference.
2. Description of the Related Art
Optical communication technology using light as a transmission medium of information is becoming widespread. To implement such the optical communication technology, an optical module is used in which optical components including a light emitting element, light receiving element, or a like are mounted on an optical electronic substrate; and in which the optical components are optically coupled through an optical waveguide. To carry out such optical transmission, it is required that optical transmission loss (optical attenuation) of an optical signal be reduced to cause the optical signal to be transmitted through the optical waveguide.
FIG. 15 is a schematic top view showing configurations of a conventional optical module. In the conventional optical module, as shown in FIG. 15, a light emitting element 102 such a laser diode and a light receiving element 103 such a photodiode or a like are mounted on an optical electronic substrate 101 made up of a semiconductor substrate or a like and the light emitting element 102 is optically coupled to the light receiving element 103 through an optical waveguide 104 formed on an optical electronic substrate 101. As a material for the optical waveguide 104, conventionally, a glass material exhibiting small optical transmission loss is preferably used. The glass material, since its optical transmission loss is as small as about 0.01 dB (decibels)/cm, exhibits an excellent optical transmission characteristic.
However, the glass material has a drawback in machinability or processibility, that is, the glass material is not suitable for microfabrication and it is difficult to apply the glass material to an optical waveguide with a comparatively large length, such as the waveguide being 10 cm or longer. Therefore, use of the optical waveguide made of the glass material is limited to applications where the optical waveguide, even when its lenghth is small, can provide much usefulness.
From a viewpoint described above, an organic resin made from, for example, polyimide tends to be used widely as the material for the optical waveguide having excellent processibility or machinability. When such an organic material for the optical waveguide is employed, by making the most of its excellent machinability or processibility, it is possible to implement an optical module in which the optical waveguide is mounted in a comparatively small space on an optical electronic substrate.
However, the conventional optical module has a problem even if it uses such the organic material. Though the optical waveguide with a comparatively large length can be formed by using such the organic material being excellent in the machinability or processibility, it has a defect in that optical transmission loss on the optical waveguide made up of the organic material is large, which makes it difficult to be applied to practical use. In the case of formation of the optical waveguide by using, for example, polyimide, since the polyimide provides the optical transmission loss of about 0.3 dB/cm, when the optical waveguide being, for example, 10 cm long formed by using the polyimide is used, an amount of light having passed through the optical waveguide is attenuated to a half. Moreover, an amount of the light having passed through the optical waveguide being 30 cm long attenuates to about one tenth.
In view of the above, it is an object of the present invention to provide an optical module and its manufacturing method which are capable of forming an optical waveguide by making the most of characteristics of a material exhibiting small optical transmission loss and having excellent machinability or processibility.
According to a first aspect of the present invention, there is provided an optical module for optically coupling a first optical waveguide constructed using a first film in which a core layer is coated with a clad layer and a second optical waveguide constructed using a second film in which a core layer is coated with a clad layer, including:
an optical waveguide sheet having the first optical waveguide in which the first film is bonded to a base substrate with a metal layer interposed between the first film and the base substrate and in which an aperture portion is formed in a desired region of the first film; and
an optical component having a second optical waveguide in which the core layer in the second film is formed in a parabolic shape;
wherein the optical component is placed in the aperture portion in the optical waveguide sheet and wherein an end face of a large diameter portion in the parabolic-shaped core layer in the optical component is disposed so as to be opposite to an end face of the core layer in the first optical waveguide in the optical waveguide sheet so that the first optical waveguide and the second optical waveguide are optically coupled to each other.
According to a second aspect of the present invention, there is provided an optical module for optically coupling a first optical waveguide constructed using a first film in which first and second faces of a core layer are coated respectively with a first clad layer and a second clad layer and a second optical waveguide constructed using a second film in which first and second faces of a core layer are coated respectively with a first clad layer and a second clad layer, including:
an optical waveguide sheet having a first optical waveguide in which the first film is bonded to a base substrate with a metal layer interposed between the first film and the base substrate and in which an aperture portion is formed in a desired region of the first film where the metal layer is exposed;
an optical component having a second optical waveguide in which the core layer in the second film is formed in a parabolic shape;
wherein the optical component is placed in the aperture portion in the optical waveguide sheet and wherein an end face of a large diameter portion in the parabolic-shaped core layer in the optical component is disposed so as to be opposite to an end face of the core layer in the first optical waveguide in the optical waveguide sheet so that the first optical waveguide and the second optical waveguide are optically coupled to each other.
In the foregoing, a preferable mode is one wherein the core layer of the first optical waveguide and the core layer of the second optical waveguide are formed so that heights of the core layer in the first optical waveguide and of the core layer in the second optical waveguide are same on the base substrate.
According to a third aspect of the present invention, there is provided an optical module for optically coupling a first optical waveguide constructed using a first film in which a core layer is coated with a clad layer and a second optical waveguide constructed using a second film in which a core layer is coated with a clad layer, including:
an optical waveguide sheet having a first optical waveguide in which the first film is bonded to a base substrate with a metal layer interposed between the first film and the base substrate and in which an aperture portion is formed in a desired region of the first film where the core layer is exposed;
an optical component having a second optical waveguide in which the core layer in the second film is formed in a parabolic shape and in which a thin film layer is formed so that the core layer in the second film is coated with the thin film layer; and
wherein the optical component is placed in the aperture portion in the optical waveguide sheet wherein the core layer in the optical waveguide of the optical component is disposed so as to be opposite to the core layer in the first optical waveguide in the optical waveguide sheet with the thin film being interposed between the core layer in the first optical waveguide and the core layer in the second optical waveguide so that the first optical waveguide and the second optical waveguide are optically coupled to each other.
In the foregoing, a preferable mode is one wherein the clad layer of the first film is made up of a first clad layer and a second clad layer which cover first and second faces of the core layer respectively.
Also, a preferable mode is one wherein the second clad layer, the core layer and the first clad layer are made up of an organic resin.
Also, a preferable mode is one wherein the second clad layer is made of a glass material and wherein the core layer and first clad layer are made of an organic resin.
Also, a preferable mode is one wherein the first clad layer is made of an organic resin and the core layer and second clad layer are made of a glass material.
Also, a preferable mode is one wherein a first wiring pattern is formed on the base substrate in the optical waveguide sheet while a second wiring pattern corresponding to the first wiring pattern is formed in the optical component wherein the first wiring pattern and the second wiring pattern are connected to each other.
Also, a preferable mode is one that wherein includes an optical fiber binding component, instead of the optical component, wherein the optical fiber binding component is disposed in the aperture portion in the optical waveguide sheet and wherein the second optical waveguide in the optical fiber binding component is disposed so as to be opposite to the first optical waveguide in the optical waveguide sheet so that the first optical waveguide and the second optical waveguide are optically coupled.
Also, a preferable mode is one wherein specular treads are formed at midpoints of an optical path in the first optical waveguide which are used to totally reflect light and to change a direction of the optical path to a perpendicular direction.
Also, a preferable mode is one wherein an end face of a large diameter portion of the core layer in the second optical waveguide is disposed so as to be opposite to an end of the core layer in the first optical waveguide in a state being inclined relative to an optical axis.
According to a fourth aspect of the present invention, there is provided a method for manufacturing an optical module for optically coupling a first optical waveguide and a second optical waveguide, including:
a first process of forming an optical waveguide sheet by bonding a first film in which a first face and a second face of a core layer made of an organic resin are coated respectively with a first clad layer and a second clad layer made of an organic resin to a base substrate with a metal layer being interposed between the first film and the base substrate;
a second process of forming a first optical waveguide by performing abrasion processing using ultraviolet laser at a desired region of the first film in the optical waveguide sheet to form an aperture portion with the metal layer being exposed; and
a third process of mounting an optical component having a second optical waveguide formed in a manner that a core layer in a second film has a parabolic shape in the aperture portion and placing an end face of a large diameter portion of the core layer having the parabolic shape in the optical component so as to be disposed opposite to an end face of the core layer in the first optical waveguide in the optical waveguide sheet.
According to a fifth aspect of the present invention, there is provided a method for manufacturing an optical module for optically coupling a first optical waveguide and a second optical waveguide to each other, including:
a first process of forming an optical waveguide sheet by bonding a first film in which a first face and a second face of a core layer made of an organic resin are coated respectively with a first clad layer and a second clad layer made of a glass material to a base substrate with a metal layer being interposed between the first film and the base substrate;
a second process of forming a first optical waveguide by performing abrasion processing using ultraviolet laser at a desired region of the first film in the optical waveguide sheet to form an aperture portion with the second clad layer being exposed; and
a third process of mounting an optical component having a second optical waveguide formed in a manner that a core layer in a second film has a parabolic shape in the aperture portion and placing an end face of a large diameter portion of the core layer having the parabolic shape in the optical component so as to be disposed opposite to an end face of the core layer in the first optical waveguide in the optical waveguide sheet.
According to a sixth aspect of the present invention, there is provided a method for manufacturing an optical module for optically coupling a first optical waveguide and a second optical waveguide to each other, including:
a first process of forming an optical waveguide sheet by bonding a first film in which a first face and a second face of a core layer made of a glass material are coated respectively with a first clad layer made of an organic resin and a second clad layer made of a glass material to a base substrate with a metal layer being interposed between the first film and the base substrate;
a second process of forming a first optical waveguide by performing abrasion processing using ultraviolet laser at a desired region of the first film in the optical waveguide sheet to form an aperture portion with the core layer being exposed; and
a third process of mounting an optical component having a second optical waveguide in which a core layer of the second film is formed so as to have a parabolic shape and a thin film layer formed so as to cover the core layer of the second optical waveguide in the aperture portion and placing the core layer of the second optical waveguide so as to be disposed opposite to the core layer in the first optical waveguide in the optical waveguide sheet.
With above configurations, the first optical waveguide is formed using small optical transmission loss and the second parabolic-shaped optical waveguide is formed by using a material being excellent in machinability and processibility and the first optical waveguide and the second optical waveguide are optically coupled and, therefore, even when the optically-coupled waveguide being comparatively long is formed, it is possible to reduce optical transmission loss to a degree to which no practical inconvenience is produced. As a result, the optically-coupled waveguide can be formed by making the most of characteristics of materials having small optical transmission loss and excellent machinability or processibilty.